Once the match has started, tabbing (Alt+Tab) to another page, and then tabbing back to League appears to cause a bug splat.
I was in game and realized that almost every time i tabbed out and back in the game would bug splat.
Specifically I was using the Lancer Rogue Blitzcrank skin, and a World Breaker Nautilus on my team relayed that he was going through the same problem.
The client itself does not crash and remains open for you to reconnect to the match. Tabbing out and in during the loading screen does not cause a bug splat.
I will continue to test this with other champs and skins.
Main account is on NA servers